AN ABYSS BETWEEN THE AMERICAN AND CENTRAL-EUROPEAN VEGETATION
CLASSIFICATION SYSTEMS

From: Adolf Ceska [aceska@telus.net]

"Kdyz dva delaji totez, neni to totez!" (When two [people] are
doing the same thing, it is not the same.) Czech proverb

If you compare American and Central-European approaches to
vegetation classification, you can see many similarities. Both
the North American and the Central- European schools place their
the major emphases on the species composition, and they both use
lists of species (releves) for sampling and they arrive at a
certain hierarchy of vegetation units. Most of these approaches
are driven by the applications these schools are serving.

Joerg Ewald, who wrote our leading article in BEN # 326 (Ewald
2004), analyzed the differences between Central European
phytosociology (CEPS) and Anglo-American plant ecology (AAPE) in
his earlier essay on phytosociology (Ewald 2003). When reading
his article I realized one most important difference between
CEPS and AAPE:

Whereas the vegetation classification in the CEPS is built from
the bottom up, in AAPE the vegetation classification is built
from the top down.

In CEPS, releves are actual building blocks of "syntaxonomical
units". Field work is aimed to obtain a large number of
vegetation samples (releves). There are two important conditions
the releves have to meet: 1) they have to be taken from areas
with ± homogeneous vegetation cover, and 2) the plots have to
be larger than the so-called minimal area. In the next step,
releves are tabulated and in the traditional table method,
similar releves are clustered together and corresponding species
that characterize those clusters are also separated from the
species that seem to be just randomly occurring throughout the
samples.

The table technique is an essentially agglomerative technique
and the result depends on the author's skills and experience.
The classification is achieved by repeated transcribing and
shuffling of the species/releve table. The final vegetation
table was considered a touch stone of vegetation classification.
Our computer program (Ceska & Roemer 1971) was a good
approximation of this mostly intuitive technique; unfortunately,
it has not made it beyond its DOS microcomputer version
"COENOS". At this moment, JUICE program (Tichy 2002) is one of
the best computer programs for the table sorting technique.

In the AAPE, releves are collected in a similar way to that in
CEPS. In AAPE, more emphasis is given to various ordination
techniques. If the classification is the final product, it is
usually achieved from the top down: the vegetation of a certain
area is divided into smaller and smaller units. In many cases,
releves are used as an illustration of these units, not as real
building blocks.

Classifications produced by the AAPE are clear-cut when we look
at the higher units, and with the consequent splitting, the
lower units become less defined. On the other hand, whenever the
CEPS approach has been applied to the North American vegetation,
the lower vegetation units, namely associations, were well
defined, but the authors invariably struggled with the
definition of higher units. Consequently, the higher units
recognized by CEPS applications did not meet those of the AAPE
higher units.

In his Critique, Ewald (2003) predicts that in spite of all its
problems, vegetation classification will remain an important
field of applied phytosociology. He writes: " ... we should
abandon the illusion of the ultimate all-purpose classification.
We have to learn to treat classifications as conjectural models
that must be judged by explicit criteria of purpose, internal
consistency, external validity and predictive capacity." In this
process, the Central European approaches should be taken
seriously. Will we eventually go from the bottom up, or will we
continue going from top down?

References

Ceska, A. & H. Roemer. 1971.

A computer program for identifying
species-releve groups in vegetation studies. Vegetatio 23:
255-277.

Other than dealing with the many European plants now naturalized
in our area, this work is not directly relevant to the botany of
the Pacific Northwest. However, this work is a model interactive
DVD-ROM flora that points to the direction our future floras
must and will take, although the trusty old paper copy,
preferably as a compact "field flora" (for my review of Stace's
1999 Field flora of the British Isles see Taxon 48: 623-
624), will still be needed outdoors on strenuous hunts to bag
taxa.

The case for the Interactive flora of the British Isles: A
digital encyclopedia (hereafter as IFBI) justifiably touts:
"This DVD-ROM holds 3.3 gigabytes of information and truly
breaks new ground in the field of plant identification and
information provision." IFBI contains an incredible amount of
readily accessible information. The base is "a new and extended
version" of Stace's New flora of the British Isles, 2nd ed.
(1997), plus the maps from C.D. Preston et al.'s New atlas of
the British & Irish flora (2002) (for my reviews see,
respectively, Taxon 47: 218-219, 52: 884- 885). This
information for 3525 species and infraspecific taxa (maps,
morphology, taxonomy, and Latin and common names) is
supplemented by some 2000 line drawings and about 6500 color
photos. Components include (see contents) interactive
identification (to family and below), searchable distribution,
word and phrase search, a bibliography, and hyperlinked
glossary.

This is one of many taxonomic CD-ROMs and DVD-ROMs obtainable
from the Expert Center for Taxonomic Identification (ETI--
http://www.eti.uva.nl/). This non-profit foundation based in Amsterdam
is "dedicated to improve on a global scale the quantity, quality
and accessibility of taxonomic information, based on an
initiative of UNESCO," and to achieve this purpose creates,
develops, and distributions at low cost various computer
software tools.

I await the day when an American flora, preferably Californian,
is available on DVD-ROM and has the excellence and flexibility
of digiStace. To twist an old adage: Trying it is believing it.
Now get it. -- Rudolf Schmid, UC

EPILOGUE 2004

Many thanks to all of you who contributed to BEN in 2004 with
your articles, to my team of editors (Jan Kirkby et al.), our
BEN web master (Scott Russell), our mailing list host the Victoria Free-Net
Association, and to George & J.G. Smith (The Glenlivet Distillery),
who have never failed to elevate my spirits.
Happy Winter Solstice and all the best in the coming year 2005!
Bottoms up! - Adolf Ceska